title: Determination of hydrazines by chip electrophoresis with contactless conductivity detection.
abstract: In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1-dimethylhydrazine (UDMH)) were separated within < 30 s at a separation voltage of 3.8 kV using a L(-)-histidine/2-(N-morpholinoethanesulfonic acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound-assisted headspace single-drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real-world applications.
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Regensburg, Germany.
authors.forename: Ashwini
authors.initials: A
authors.lastname: Kumar
authors.forename: Jacob
authors.initials: J
authors.lastname: Burns
authors.forename: Werner
authors.initials: W
authors.lastname: Hoffmann
authors.forename: Horst
authors.initials: H
authors.lastname: Demattio
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Malik
authors.forename: Frank-Michael
authors.initials: FM
authors.lastname: Matysik
mesh_terms: D004553:Electric Conductivity; D046209:Electrophoresis, Microchip / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis; D006834:Hydrazines / Q000032:analysis*; D016014:Linear Models; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry; D012680:Sensitivity and Specificity; D012987:Soil / Q000737:chemistry; D052617:Solid Phase Microextraction; D013010:Sonication
chemical_list: D004785:Environmental Pollutants; D006834:Hydrazines; D012987:Soil